Chemistry of inorganic compounds – With additive
Patent
1993-04-27
1994-10-18
Langel, Wayne
Chemistry of inorganic compounds
With additive
423279, 423281, C01B 1512, C01B 3512
Patent
active
053566068
DESCRIPTION:
BRIEF SUMMARY
PEROXIDIC COMPOSITIONS
The present invention relates to peroxidic compositions and more particularly to compositions in liquid form which additionally contain an alkali metal oxyboron compound in which the alkali metal to boron mole ratio is substoichiometric.
Peroxid-Chemie GmbH, which is an Interox company, as is the present applicants, has been conducting research into aqueous peroxidic solutions containing an alkali metal oxyboron compound. They have prepared and identified a range of compositions which are particularly suitable for producing an alkali metal perborate in microcrystalline form in a subsequent process. In their compositions, the alkali metal to boron mole ratio is substoichiometric and preferably ranges from 0.33:1 to 0.67:1. Colloquially, the aqueous peroxidic compositions can be called perborate solutions, without implying which molecular structure for the species is present. They have also described subsequent processing steps in which alkali is introduced into their perborate solutions, preferably to attain an equivalent ratio of alkali to boron of about 0.9: 1 to 1.1:1 and the resultant mixture is cooled.
The liquid perborate compositions described by Peroxid Chemie, and particularly within their preferred range, demonstrate an inherent degree of physical stability that is surprisingly good. However, extended trials on the liquid perborate solutions have shown that precipitation of a solid material can occur, especially after extended periods of storage. Precipitation is unwanted for a number of important reasons, but primarily because it denies to the customer of the composition the opportunity to obtain microcrystals in a controlled precipitation procedure. Premature crystallisation can also cause blockages in transportation lines or storage vessels.
Although it is feasible for the manufacturing process for the liquid perborate solutions to be followed with little delay by further processing, such as a controlled microcrystallisation process and the two processes to be conducted on the same site, it is often more convenient for the subsequent processing to be carried out by the customer rather than the manufacturer of the liquid perborate solutions. The various processing activities, in consequence, may be conducted at different locations that may be a long way apart. Multi-site procedures entail transportation of the liquid perborate solutions in bulk and can also entail their storage for extended periods of time, before, during and/or after transportation. The risk of precipitation can be exacerbated when the solutions are subject to the range of stresses, associated with the handling in bulk of chemicals, including temperature fluctuations and physical shaking. Consequently, it would be prudent to extend the safety margin for the compositions, i.e. enhance their physical stability, so that they are even better able to withstand the rigours of transportation and storage and resist for a longer period the threat of uncontrolled precipitation.
According to the present invention, there is provided a process for enhancing the physical stability of an aqueous peroxidic solution of an alkali metal oxyboron compound containing alkali metal to boron in a substoichiometric mole ratio which is characterised by introducing into the solution an effective amount of cyclohexane-1,2-diaminotetra(methylene phosphonic acid) or water soluble salt thereof.
In a second and closely related aspect of the present invention, there are compositions having enhanced physical stability comprising an aqueous peroxidic solution of an alkali metal oxyboron compound containing alkali metal to boron in a substoichiometric mole ratio into which there has introduced an effective amount of cyclohexane-1,2-diaminotetramethylene phosphonic acid) or water soluble salt thereof.
By the use of an effective amount of cyclohexane-1,2-diaminotetra(methylene phosphonic acid), often abbreviated herein to CDTMPA, in acid or salt form, it is possible to keep the aqueous solutions according to the invention for longer before s
REFERENCES:
patent: 1101449 (1914-06-01), Kemmerich
patent: 2155704 (1939-04-01), Goodall et al.
patent: 3960888 (1976-06-01), Ploger et al.
patent: 4117086 (1978-09-01), Ploger
patent: 4849198 (1989-07-01), Ruhs
World Patents Index Latest, Week 16, Derwent Publications Ltd., London, GB; AN 85-095250 & JP,A,60 042 206 (Nippon Peroxide K.K.) 6 Mar. 1985.
Horne Graham R.
Troughton Nicholas A.
Langel Wayne
Solvay Interox Limited
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